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. Author manuscript; available in PMC: 2020 Dec 18.
Published in final edited form as: Org Biomol Chem. 2019 Dec 18;18(1):36–40. doi: 10.1039/c9ob02099c

Scheme 1.

Scheme 1

Synthesis of probe A (9). (i) ethyl acrylate, Grubb’s second generation catalyst, DCM, 25 °C, 10 h, 75%; (ii) oxalyl chloride, cat. DMF, DCM, 0 °C, 20 min; (iii) bis(trimethylsilyl)acetylene, AlCl3, DCM, 0 °C, 3 h, 26% ~2 steps; (iv) freshly prepared Terashima reagent (see Experimental section), −78 °C, 98%, ee 80%; (v) TBDMSCl, imidazole, DMF, 25 °C, 2.5 h, 94%; (vi) LiOH·H2O, dioxane, H2O, 60 °C, 12 h, 50%; (vii) oxalyl chloride, cat DMF, DCM, 0 °C, 20 min; (viii) benzocaine, DIEA, DCM, 0 °C, 1 h, 87% ~2 steps; (ix) HF in H2O, MeCN, 25 °C, 1 h, 85%; (x) CCl3CN, DBU, DCM, 25 °C, 2 h; (xi) 17, TMSOTf, DCM, 0 °C, 1 h, 50% ~2 steps; (xii) TBAF, THF, 25 °C, 12 h, 93%; (xiii) LiOH·H2O, dioxane, H2O, 60 °C, 12 h, 62%.